The studies carried out under auspices of this grant aim to elucidate several aspects of the gonococcal surface especially as they relate to interactions of the gonococci with other similar organisms or with cells of the host. The interactions currently under study are gonococcus-leukocyte association and intergonococcal aggregation. During the coming year, work will be directed toward clear definition of the protein(s) responsible for leukocyte-association characteristics of gonococci, toward defining the character of proteins associated with gonococcal aggregation and trypsin sensitivity, and at further clarification of the relationships of protein patterns with several other phenotypes found in isolates from patients with acute gonorrhea. In addition, the IgA protease secreted by gonococci will be purified to homogeneity and several studies aimed at elucidating the relationship of this enzyme to pathogenesis of acute gonorrhea will be carried out. BIBLIOGRAPHIC REFERENCES: James, J. F., and J. Swanson. 1977. The capsule of the gonococcus. J. Exp. Med. (in press). Swanson, J., G. King, and B. Zeligs. 1975. Studies on gonococcus infection. VII. In vitro killing of gonococci by human leukocytes. Infection & Immunity 11:65.